1. Technical Field
The present disclosure relates to heat dissipation devices, and particularly to a heat dissipation fan.
2. Description of the Related Art
With the continuing development of electronics technology, electronic packages such as CPUs (central processing units) employed in electronic devices are generating more and more heat. The heat requires immediate dissipation in order that the CPU and the electronic device can continue to operate stably. A heat dissipation device such as a heat dissipation fan is commonly used in combination with a heat sink for cooling the CPU.
A conventional heat dissipation fan includes a housing and an impeller receiving in the housing. The impeller includes a plurality of blades. An inner sidewall of the housing is usually configured vertically and facing an end of each blades. The ends of the blades are usually configured vertically too. During operation of the heat dissipation device, the blades of the impeller rotate and drive air to evacuate heat from a fin assembly to the ambient environment through an air channel defined between the sidewall of the housing and the ends of the blades. However, a height of the sidewall of the housing is larger than that of the blades. An air pressure which is formed in an area of the air channel is stronger than that in other areas, thereby resulting in a non-uniform air pressure. Thus the rotation of the blades will generate a reverse involved airflow. When this happens, the impeller is said to be in a “floating” condition and is inclined to generate noise and lose energy, which may be annoying or even unacceptable.
What is desired, therefore, is a heat dissipation fan which can overcome the above-described shortcomings.